This invention relates to the damping of vibration, and more particularly to the damping of vibration in rotating devices. The invention has particular application to the attenuation of screech noise from railroad wheels.
Assemblies for damping vibration in rotating devices are known. Many involve the use of relatively heavy damping assemblies, which is undesirable from the standpoint of adding an additional load to the rotating device as well as safety. In the present invention, a lightweight damping assembly is provided.
The related application cross-referenced above involves a vibration damping assembly for a wheel or the like that includes an annular groove in a surface of the wheel and coaxial with the wheel axis. A viscoelastic damping material subject to shear deformation during rotation of the wheel is positioned within the groove against the surface of the groove, and an annular metal ring is positioned in the groove against the viscoelastic damping material, with the damping material sandwiched between the ring and wheel. It was indicated in that application that it is preferable to position the damping assembly on the wheel so that it does not extend outwardly beyond the plane defining the edge of the wheel so as to protect the damping assembly from external forces that might damage it.
The present invention involves a vibration damping assembly similar to that of the related application cross-referenced above. It utilizes an annular groove in a surface of the wheel, in which one leg of a channel member generally U-shaped cross-section is positioned, substantially encased therein by a vibration damping material. The remaining portion of the channel member extends close to areas of the wheel that are adjacent to the groove, and vibration damping material is sandwiched between these adjacent areas and the channel member. Preferably, the annular groove is in the inner rim area of the wheel, adjacent to the outer rim area, and the channel member is positioned so that one leg thereof is encased, as noted, within the groove by vibration damping material, while the other leg thereof extends adjacent to the outer rim area of the wheel. By sandwiching damping material beneath the entire channel member, greater vibration damping is achieved than possible through the use only of vibration damping material within the annular groove as in the cross-referenced application. The vibration damping material utilized herein may be material which is subject to shear deformation as the wheel is rotated, as well as material which is subject to deformation in tension and compression. The damping assembly is firmly positioned on the wheel, and is not subject to being damaged or dislodged easily by external forces, and so may extend beyond the plane of the edge of the wheel.
The invention will be more completely understood by reference to the following detailed description.